Advanced Materials Research Vols. 524-527

Abstract: On the engineering background of coal mine roadway orbit, according to the destruction of its original roadway, the paper have analyzed the situation of the deformation in the roadway , using the method of numerical simulation. Besides, it also determined the stress distribution and the forces supporting of roadway in the deformation process. Geological conditions, support patterns and bad construction are considered as the main factors of roadway damage and new support method is given. Numerical simulation method is used to study mechanism about anchor rod, anchor cable and anchor mesh coupled with the surrounding, bottom corner anchor rod and grouting to determine the optimal program. The new program is applied to the practice field and monitored, indicating that the application has a very good effect.

Abstract: The permeability of coal seam is an important parameter for the gas extraction and gas outburst control. However, most of the coal seams are low-permeability with outstanding characteristic in China. Therefore，it is a good technology to provide the theoretical basis for increasing the permeability of low-gas- permeability coal seam by shocking with high-pressure air. Based on the percolation theory of porous media and combining the gas pressure change after shocking the coal seam with high-pressure air, the solid-gas coupled mathematical model is presented for the flow in the coal seam. By applying the software, the numerical simulation is computed and analyzed for the gas pressure evolution owing to the multi-spot continuous shocking the coal seam by the high-pressure air under the different pressure values and strata pressure.

Abstract: Combined with forced roof caving technology using pre-splitting and blasting methods with deep or shallow borehole, this research illustrates the construction environment and implementation methods in detail, analyzes implementation effect and strata behaviors of working face at the length, and discusses the features and adaptive conditions of forced roof caving technology with pre-splitting and blasting at close range, which has a certain directive significance and reference value to engineering practices with similar conditions.

Abstract: In this paper, it has been studied that types and mechanical properties of tailings silt in Zhuziqing tailings dam based on the Zhuziqing tailings’ deposition characteristics, particles size distribution test, physical and mechanical properties test. Then it has been studied subsequently by the dynamic triaxial test, wave velocity test and standard penetration test for tailings silt that the dynamic characteristics, dynamic strength and vibration liquefaction of the tailing silt. Results show that the tailings silt in tailings pond is graded well. Under the condition of isotropic or anisotropic consolidation, dynamic shear modulus of tailings silt increase as the dynamic shear strain decreasing and increase as the increase of confining pressure or consolidation ratio. But the variation law on damping ratio of tailings silt is just opposite to that of dynamic shear modulus. Results also show that there is more liquefied possibility over the seventh sub-dam in the tailings dam, and the liquefied possibility position locates at the place from new sub-dam to deposited beach in tailing pond.

Abstract: Based on the geological conditions and specific mining technology conditions of the 11014 mining face of Panbei mine in HuaiNan mining group ,using the FLAC3D software, simulate the stress distribution rule and disruption field distribution rule of surrounding rock of Fully-Mechanized face enhancing the upper limit for coal mining along the tendency and trend of coal seam by different mining speed of 6 m/d, 4 m/d and 2 m/d. draw the conclusion that enhancing the mining speed can alleviate the pressure of the working face ,improve the working face mechanical environment,and reduce the extent of the failure field.It provides the theory basis and reference for Fully-Mechanized face enhancing the upper limit for coal mining under similar conditions.

Abstract: Based on the deep soft rock creep mechanism, according to the physical characteristics of bauxitic mudstone in ingate at the level of -1015 m of Kong Zhuang colliery, we solved the technical difficult problem of choosing anchor points of soft rock supporting roadway in ingate. Using high strength and low relaxation steel strand to reinforce by crossed anchor, in combination with the depth hole grouting technology, improve pressure-bearing capacity of wall rock in the ingate, safe passage and drainage pipe area. We analyze the stress distribution characteristics of rock mass, contrasting on the stress distribution at the end of partially grouted bolt and the rock mass. Practice shows that crossed anchor rock mass has triaxial compression over all, the bunch body has a single structure, and it is easily to be analyzed. We not only control the roof settling in the area of ingate is, but also solve the floor heave problem in safe passage and drainage pipe area.

Abstract: soft rock; parameter; bolt-mesh-anchor support; ground pressure.

Abstract: Under the background of the hydrogeology conditions of the first working face of 11 coal seam in LuXin coal mine, theoretical formula prediction and numerical simulation were used to research the influence of mining height on the growth altitude of water flowing fractured zone. According to the requirement of the minimum thickness of waterproof coal pillars, the reasonable mining height was confirmed to be 3m. It was proved by similar material simulation that the maximum height of water flowing fractured zone was about 39.5m when the mining height is 3m, which was consistent with results of numerical simulation, and the thickness of protective layer was 23.5m, which ensured the safety of mining.

Abstract: It’s an effective ways to hydraulic-cutting seam for drainage that solves gas disaster and prevents impact pressure in mining. In order to get the seepage rule and productivity prediction of hydraulic-cutting for coal-bed methane(CBM) mining, the theory of seepage mechanics combined with elastic-plastic mechanics was used to set up a mathematical model and the boundary conditions and initial conditions was given meanwhile. The Matlab software was used to obtain the variation rule of coal-bed stress field, gas pressure field and gas extraction yield. The simulation results show that the effective stress is released after hydraulic-cutting seam used and the effect of unload is obvious along seam; the numbers of crack and fracture increases and the length and width of crack and fracture improve. So the permeability of coal seam enhanced and the absorbed gas disorpted greatly from coal seam because of the increase of contact area. The extraction yield of gas is bigger to hydraulic-cutting seam than conventional drilling. The simulation results show the advantage of hydraulic-cutting seam for CBM extraction and the method of simulation is significant to the execution project and productivity prediction of hydraulic-cutting seam for CBM industrial production increasing technology.

Abstract: The coal bed methane is an important part of the Chinese energy. To finding some effect ways to collect gas during the coal mining process will increasing the using rate of coal mine and reducing greenhouse gas emission. The most effective way is coal and gas co-mining, and the main technology of the coal and gas co-mining are gas pre-extraction before mining, gas extraction of pressure relief, gas extraction of adjacent layer, gas extraction of goaf and top fractured zone, Gas extraction of excavation roadway and so on. Based on the technique system of coal and gas co-mining and the key problems existing in coal and gas extraction technology, to improve energy efficiency and reduce coal mine disaster.